//:C06:ComposeFinal.cpp {-edg}
// An adaptable composer.
#include <cassert>
#include <__functional/unary_function.h>
#include <algorithm>
#include <cassert>
#include <functional>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
#include "NumStringGen.h"
using namespace std;

template<typename F1, typename F2> 
class unary_composer : public unary_function<typename F2::argument_type, typename F1::result_type>
{
    F1 f1;
    F2 f2;
    public:
        unary_composer(F1 f1, F2 f2) : f1(f1), f2(f2){}
        typename F1::result_type operator()(typename F2::argument_type x)
        {
            return f1(f2(x));
        } 
};

template<typename F1, typename F2>
unary_composer<F1, F2> compose(F1 f1, F2 f2)
{
    return unary_composer<F1, F2>(f1, f2);
}

int main(void)
{
    const int SZ = 9;
    vector<string> vs(SZ);
    // Fill it with random number strings:
    generate(vs.begin(), vs.end(), NumStringGen());
    copy(vs.begin(), vs.end(),
        ostream_iterator<string>(cout, "\t"));
    cout << endl;
    vector<double> vd;
    transform(vs.begin(), vs.end(), back_inserter(vd),  
        compose(ptr_fun(atof), mem_fun_ref(&string::c_str)));
    copy(vd.begin(), vd.end(), ostream_iterator<double>(cout , "\t"));
    cout << endl;
}